Deploying Internet Protocol (IP) telephone systems allow enterprises and individuals to transport voice communication over a packet-based network and thereby avoid leasing traditional circuit-switched telephone lines that constitute the public switched telephone network (PSTN). Beyond voice communication, IP telephony provides extensive voice and data services, including instant messaging, call waiting, caller identification, and conferencing, as well as connectivity to legacy telephone networks.
IP telephone systems, such as an IP Private Branch eXchange (IP-PBX) phone system that comprises an IP-PBX and one or more IP telephones, include coder-decoders (codecs) to convert analog waveforms into a digital bitstream for transmission over an IP network and to reconstruct analog waveforms from a digital bitstream received via the IP network. In addition to analog-to-digital and digital-to-analog conversion, IP telephone systems provide signal processing functionality to voice calls, including voice compression/decompression, echo cancellation, silence suppression, and teleconference mixing. For example, individual IP telephones include codecs to provide signal processing functionality for endpoint use. An IP-PBX gateway coupling the IP telephone system to the PSTN and/or analog telephones also include dedicated codecs to provide signal processing functions to bridge traditional voice and digital bitstream voice networks.